In weapons which load, then extract a cartridge or shell past projecting edges between a sliding breech block and a breech plate, there is potential for difficulty caused by misalignment of the pieces. For long cartridges, misalignment is not a problem since the guiding of a long cartridge case starts in the chamber during loading or in other words remains during ejection when the base of the cartridge has passed the edge between the breech block and plate, a feature which is not available when the cartridge is sufficiently short and the cartridge is out of the barrel before its base has passed that edge.
In general, the sliding breech block will not be aligned with the breech plate to form a smooth bore half cylinder, and the breech block will take a different position with respect to the breech plate during loading and ejection since the breech block rebounds against the adjacent edge of the breech plate during ejection, while in loading the same edge of the breech plate overlaps the same edge of the elevated breech block. This means that each short cartridge must be loaded into the chamber by hand and that during ejection the cartridge strikes the projecting edge and either flies out of the chamber in an uncontrolled manner or is stuck.
In the prior art, there is a loading aid that does not assist in the ejection cycle (DT-PS No. 1,068,589) in the form of a projecting member attached to the breech plate with an opening coaxial with the barrel. The effect of this member and of a hold-down clamp is that it is more difficult for the point of a relatively long cartridge to strike the rear edge of the loading chamber and that the entry speed of the cartridge is reduced. Also, because of the guiding, the force with which the cartridge is pushed into the barrel is reduced.